Other types of sensors may be used to determine the concentration of a wash aid. Examples of such sensors include a resistivity sensor having a pair of electrodes in contact with the wash liquid, a pH sensor, an oxidation/reduction sensor, a chemical sensor, and the like, capable of generating a signal proportional to the concentration of the wash aid.
The use of the refractive index sensor assembly enables precise control of the volume of wash aid dispensed. For example, if a selected laundering cycle and wash load size correspond with a predetermined volume of wash aid having a selected concentration to provide optimal laundering, the refractive index sensor assembly may determine the concentration of the wash aid, and the controller 24 may control the dispensing valve 26 to dispense the predetermined volume of wash aid for the selected laundering cycle and wash load size. Alternatively, if the concentration of the wash aid may be input by a user through the user interface 22 into the controller 24, the refractive index sensor assembly may confirm that the concentration of the wash aid in the bulk wash aid dispenser is indeed the concentration entered by the user. If an adjustment in volume is necessary to account for a difference in concentration from that input into the controller 24, the controller 24 may control the dispensing valve 26 to dispense the appropriate volume of wash aid.
The refractive index sensor assembly may be used in a similar manner to control the volume of wash aid dispensed from a large bulk wash aid container (not shown). The bulk container may hold a quantity of wash aid sufficient for a relatively large number of laundering cycles. The large container may not be utilized with a dispenser drawer, but may be fluidly coupled with the washing machine 10 through a dispenser fitting incorporated into the washing machine 10, in which the large container may be seated. The large container may be coupled with the washing machine 10 through a liquid-tight coupling (not shown), such as a quick-connect coupling assembly. The coupling may be fluidly connected to the valve 26, or to a dedicated dispensing valve (not shown) incorporated into the dispenser fitting.
The volume of wash aid in the bulk wash aid dispenser may be determined from the incorporation of a liquid height sensor into the dispenser. Such sensors are known to those of ordinary skill in the art. Thus, the control of the operation of the washing machine 10 may be correlated to the height, and consequently the volume, and concentration of the wash aid.
After introducing a laundry detergent having a selected concentration into the bulk wash aid dispenser and closing the dispenser drawer 20, a user may select a laundry cycle, and may adjust options such as water temperature, spin speed, and the like. After starting the selected laundry cycle, the concentration of the laundry detergent in the dispenser may be determined as described above. The controller 24 may then determine the quantity of laundry detergent to be dispensed from the dispenser based upon the laundry cycle, the weight of the laundry load, and other factors that may affect detergent volume, such as water temperature.
Alternatively, if the user has selected, for example, a 2× detergent on the user interface 22, the controller 24 may confirm that the proper concentration detergent, i.e. a 2× detergent, is present, and proceed with the laundry cycle. If, however, the user has selected, for example, a 1× detergent on the user interface 22, but has introduced 4× detergent into the dispenser, the controller 24 may determine what volume of 4× detergent should be dispensed for the selected laundry cycle, load weight, and any other factors. Alternatively, the controller 24 may terminate the laundry cycle, cause an audio or visual warning signal to be broadcast, or a combination of termination and a warning signal.
A refractive index sensor assembly utilized in a washing machine having a bulk wash aid dispenser may lead to more accurate control of the dispensing of the wash aid, since the volume of wash aid to be dispensed can be accurately determined by the controller 24 based upon the inputs from the refractive index sensor assembly, and the controller 24 can precisely control the volume of wash aid dispensed from the bulk wash aid dispenser regardless of the concentration.
FIG. 3 is a table illustrating the refractive index for different concentrations of detergent from different manufactures. It can be seen from the tabular data that there is a general correlation between the percentage of surfactant and the refractive index for a detergent. The refractive index tends to increase as the percentage of surfactant increases. This general correlation is strong enough that the refractive index may be used to determine between classes of concentrations, such as 1× and 3× detergents. Determining the refractive index of a surfactant is not the only means of identifying the concentration of the detergent. The refractive index of other detergent components, such as builders, emulsifiers, soil suspending agents, alkaline builders, optical brighteners, unit weights, and the like, may be utilized to determine the concentration of such components. While the general correlation between refractive index and percent surfactant is sufficient to determine between classes, there is variation in the refractive index within a given concentration range, which is not solely attributable to the variations of the percent surfactant. These variations are thought to be attributable to other ingredients in the detergent. These variations are also partly attributable to the fact that not all detergents in a given class, i.e. 1×, 3×, etc., have the same identical percentage of surfactant.
It has been noted that each detergent has a unique refractive index. In this way, the refractive index may be used as an identifier for a specific detergent. The refractive index may be used as “fingerprint” to identify a specific detergent regardless of its surfactant concentration. A database or table of information may be created showing the refractive index for each type of detergent. This database may be used by the controller to look up the specific detergent based on the sensed refractive index and determine the corresponding concentration.
Thus, the refractive index information may be used in at least two ways, separately or in combination, to determine the concentration of the detergent and to use that information to control the dispensing of the detergent. The first way is to use the refractive index to make a general determination regarding the class of detergent (1×, 2×, 3×, etc.). The general class determination is useful in making general distinctions, but it may not give specific information about a particular detergent's concentration. The second way is to use the refractive index to identify the detergent and look up the corresponding concentration. The look up method is useful in that the exact concentration values may be determined. For example, an advertised 1× detergent may actually have a 1.2× concentration or a 0.8× concentration.
The controller 24 can implement a technique to determine the surfactant concentration from a sensed refractive index, such as direct lookup, a comparison to a reference value, a linear regression analysis, or interpolation between stored values of refractive index greater than and less than the sensed refractive index. One implementation of this method would be to first use the refractive index to identify the detergent as this will provide the most accurate results. That is, the controller will use an appropriate method to find a match for the sensed refractive index value. The methodology may not require an exact match, but may look for a range or close fit. If a match is not found, then the refractive index may be used to make a general class determination.
FIG. 4 illustrates in greater detail an embodiment of the dispenser comprising the dispenser drawer 20 suitable for use with the automatic clothes washing machine 10. The dispenser drawer 20 is illustrated as a generally open-top box-like structure having a front wall 130, a rear wall 132, a pair of sidewalls 134, 136, and a bottom wall 138. The dispenser drawer 20 may be configured with interior walls defining a cartridge cavity 142 for receipt of a bulk dispenser cartridge 140. The dispenser cartridge 140 may contain a quantity of a wash aid, such as a laundry detergent, sealed therein behind a slidable door 143 (shown open in FIG. 4) and sufficient for several laundering cycles, for example, 8-10 laundering cycles. The use of the dispenser cartridge 140 may eliminate the need for a user to measure out a selected volume of wash aid for each laundering cycle.
The dispenser cartridge 140 may be a generally rectilinear, box-like container sized to be received within the cartridge cavity 142 of the dispenser drawer 20. The cartridge may have a front wall 144, a pair of parallel side walls 146, 148, a rear wall 150, a top wall 151 with the slidable door 143, and a bottom wall 152 defining a cartridge cavity in which the wash aid may be contained. The slidable door 143 may be formed in the top wall 151 to provide for ready refilling of the cartridge 140. Each side wall 146, 148 may be provided with a sensor window 154, 156, respectively, the sensor windows 154, 156 being aligned for the transmission of a refractive index sensor light beam through the wash aid.
Although the bulk dispenser cartridge has been described as a rectangular box-like container, the bulk dispenser cartridge may be any type of removable container configured to store multiple doses of a treating chemistry. The cartridge may have any shape and size that is receivable within the dispenser. The removable cartridge may be flexible, rigid, expandable, or collapsible. The cartridge may be fabricated of any type of material or combination of materials. Some examples of suitable cartridges are, without limitation, a plastic container, a cardboard container, a coated cardboard container, and a bladder, all of which are capable of being received within the dispenser.
The dispenser drawer 20 may incorporate the transmitter 48 and the sensor 50 therein for projection of a light beam from the transmitter 48 through the windows 154, 156 and the wash aid, to be received by the sensor 50 for determining the refractive index of the wash aid. The dispenser drawer 20 may also be configured with a suitable fluid connector for connecting the dispenser cartridge 140 into a wash aid dispensing line, such as the dispensing line 38 illustrated in FIGS. 1 and 2. The dispenser cartridge 140 may also be fluidly coupled with a valve for controlling the dispensing of a wash aid into the dispensing line, such as the dispensing valve 26 illustrated in FIGS. 1 and 2.
After the dispenser cartridge 140 has been properly installed in the dispenser drawer 20, a selected volume of wash aid may be dispensed from the dispenser cartridge 140 through operation of the dispensing valve 26 under the control of the controller 24. This may be accomplished by the user selecting a volume of wash aid on the user interface 22. Alternatively, this may be accomplished by selecting a laundering cycle on the user interface 22. The refractive index of the wash aid may then be determined, and correlated in the controller 24 to a surfactant concentration, which may then be processed by the controller 24, along with a determination of the size of the load, to automatically dispense the appropriate volume of wash aid.
FIG. 5 illustrates an alternate embodiment of a refractive index sensor 210 for incorporation into a wash aid dispenser drawer 70. The dispenser drawer 70 may be similar to the dispenser drawer 20 except that the transmitter 48, the sensor 50, the transmitter input lead 54, and the dispenser sensor output lead 58 are not used. A sensor coupling 166 may be integrated into the side wall 134, and electrically coupled with the controller 24 through a sensor lead 168. The bulk dispenser cartridge 170 differs somewhat from the bulk dispenser cartridge 140 in that the sensor windows 154, 156 are not incorporated into the side walls 146, 148.
Referring specifically to FIG. 6, the bulk dispenser cartridge 170 may be provided with an intermediate wall 200 parallel to and spaced internally from the rear wall 150 to define a sensor chamber 202 in which a sensor 210 may be located. The intermediate wall 200 may be provided with a sensor opening 214.
The side wall 146 of the cartridge 170 may incorporate a sensor junction box 204. The sensor junction box 204 may comprise one or more electrical contacts 206 for electrical coupling with complementary electrical contacts (not shown) positioned along the interior of the side wall 134 of the dispenser drawer 70 including part of the sensor coupling 166. The junction box 204 may be coupled with the sensor 210 through a suitable known wire harness 208.
A suitable refractive index sensor 210 may be a Spreeta™-R sensor manufactured by Sensata Technologies of Attleboro, Mass. The sensor 210 includes a base 216 and a housing 218. The housing may be fabricated of a clear material, such as a plastic. The housing 218 includes a glass sensing interface 228 and a reflector 230. The base 216 includes a light source 220 and a photodiode array 222. The light source 220 may comprise one or more light emitting diodes (LEDs) configured to focus light at an angle onto the sensing interface 228. A focusing apparatus 224 may be positioned above the light source 220 and may comprise an aperture 226 for focusing a light beam 232 onto the sensing interface 228. The refractive index sensor 210 may be mounted in the wash aid dispenser drawer 20 so that the sensing interface 228 may be in registry with the sensor opening 214 and can contact the wash aid.
The sensor 210 is based on the optical phenomena of surface plasmon resonance, which occurs when light interacts with a free electron material. In operation, the light from the light source 220 reflects internally off the liquid-glass interface between the sensing interface 228 and the wash aid. The light then reflects off the mirror 230 and onto the photodiode array 222. Depending on the refractive index of the liquid, light striking the surface above a certain angle will be transmitted through the liquid-glass interface instead of being internally reflected. This angle is called the critical angle. This phenomenon results in a dark area or shadow-line on the photodiode array. The location of the shadow-line is indicative of the refractive index. As the refractive index changes, the critical angle also changes and is sensed as a new shadow-line location.
When the cartridge 170 is inserted into the dispenser drawer 70, the junction box 204 may be coupled with the sensor coupling 166, thereby providing communication between the sensor 210 and the controller 24. Data from the sensor 210 corresponding to the refractive index, and thus the concentration, of the wash aid can be delivered to the controller 24 for further processing and control of the dispensing of the wash aid from the bulk dispenser cartridge 170.
The refractive index sensor 210 can also be mounted in a similar manner in a reservoir (not shown) downstream of and fluidly coupled with the dispenser drawer 70. In such a case, a quantity of wash aid can be delivered from the cartridge 170 to the reservoir, and the concentration of the wash aid determined as described above. The controller 24 will then determine the appropriate quantity of wash aid to be dispensed. The advantage of such a configuration is that a single refractive index sensor can be mounted permanently in the dispenser drawer 70 rather than in a cartridge, thereby reducing the cost of a bulk dispenser cartridge.
In either configuration, the sensing apparatus can be contained entirely on one side of the container holding the wash aid. Additionally, only one window into the wash aid is required, and fewer electrical connections are required. The washing machine 10 illustrated herein is only one example of a washing machine configuration. Several pumps may be utilized for selected functions, a fewer or greater number of valves may be utilized depending upon the selected fluid line configuration and degree of control desired, and control leads may be incorporated into the washing machine 10 based upon the components for which control by the controller 24 may be desired. While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.